Abe Makoto, Medina-Martinez Raul U, Itoh Ken-ichi, Kohno Shoji
Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata, Japan.
Med Biol Eng Comput. 2006 Nov;44(11):1017-30. doi: 10.1007/s11517-006-0075-8. Epub 2006 Oct 27.
The aim of this study was to investigate the features of the loading vectors of the temporomandibular joint (TMJ) generated during bilateral static bites at the molars and at the premolars, and to determine the major factors affecting the difference between the two loading vectors. We computed the subjects' estimated and theoretical minimum TMJ loadings under the two different bite conditions by applying the subjects' bite-force and electromyographic (EMG) data to a two-dimensional (2D) standard model of the jaw based on a rigid-body spring model of the TMJ. For a molar bite, (1) the estimated loading vector was not equal to its theoretical minimum; (2) the TMJ-loading/bite-force ratio, describing the proportion of TMJ loading, was relatively small, 0.477 on average; and (3) the estimated loading vector pointed in the direction of the central part of the articular disk's intermediate zone. For a premolar bite, on the other hand, (1) the estimated loading vector was nearly equal to its theoretical minimum; (2) the TMJ-loading/bite-force ratio was relatively large, 0.904 on average; and (3) the estimated loading vector pointed at the superior portion of the articular disk's intermediate zone. The differences between the TMJ-loading vectors for molar and premolar bites originated primarily from changes in the bite-point location.
本研究的目的是调查在双侧静态磨牙咬合和前磨牙咬合过程中颞下颌关节（TMJ）产生的负荷向量特征，并确定影响两种负荷向量差异的主要因素。通过将受试者的咬合力和肌电图（EMG）数据应用于基于TMJ刚体弹簧模型的二维（2D）标准颌骨模型，我们计算了两种不同咬合条件下受试者的估计和理论最小TMJ负荷。对于磨牙咬合，（1）估计的负荷向量不等于其理论最小值；（2）描述TMJ负荷比例的TMJ负荷/咬合力比值相对较小，平均为0.477；（3）估计的负荷向量指向关节盘中间区域中心部分的方向。另一方面，对于前磨牙咬合，（1）估计的负荷向量几乎等于其理论最小值；（2）TMJ负荷/咬合力比值相对较大，平均为0.904；（3）估计的负荷向量指向关节盘中间区域的上部。磨牙和前磨牙咬合的TMJ负荷向量之间的差异主要源于咬合点位置的变化。
